What is bycatch and why does it happen? How many tons of bycatch is caught each year?

The term bycatch refers to those non-targeted fish or other aquatic species that are unintentionally caught by the fishermen. Bycatch may differ from target species in terms of size, sex or is immature or juvenile. While fishing, some species caught incidentally which later get died overboard. According to the Organization for Economic Co-operation and Development (OECD), bycatch is "total fishing mortality, excluding that, accounted directly by the retained catch of target species." This phenomenon becomes widespread in 1970 when large numbers of dolphins were caught in tuna nets in Pacific.

The major reason for this phenomenon is contemporary nonselective fishing gear. It catches whatever comes in its path other than the desired or target species such as dolphins, turtles, seabirds, and others. Fishing methods that usually result in bycatch are long lines, trawling, and gillnets. Longlining method is used to attract swordfish, tuna, and halibut. This method uses hundreds of baited hooks which if swallowed, resulted in the death of the animal. Turtles are the most affected of longlining. Trawling, on the other hand, is a method of dragging nets in the sea by boats. It can catch marine turtles and damage the coral reefs. “Gillnets are mesh nets that allow fish to pass their heads and gill coverings through a hole in the mesh and then get stuck when they try to back out.”

About 7 million tons of fish and other marine species caught incidentally and discarded every year. This made the bycatch a serious problem and a threat to endangered species. Sometimes catch is more than the target species which tends to affect the ecosystem because the animals that are disposed of may not reproduce. Fishing industries worldwide are trying to reduce this phenomenon. They have found cheap and easy ways such as modification of fishing gear through which less number of non-target species are caught. It is still a major problem regardless of all the advancement in technologies.

Every year more than 300,000 small whales, dolphins died by getting stuck in nets. Many of the species such as Californian vaquita and New Zealand’s Maui dolphin have chances of getting extinct. Similarly, endangered turtles like loggerhead and leatherback also become a target of bycatch. “In 2007, the world learned that the baiji, a freshwater porpoise found only in China’s Yangtze River, finally succumbed to decades of incidental hooking (among other causes of mortality) and is now believed to be extinct.”

Many organizations are working to deal with this phenomenon. Innovations are made in fishing methods such as the introduction of circle hooks instead of J hooks which has more chances of being swallowed. Circle hooks are designed in a way that if get swallowed has least chances of internal bleeding. It is important that fisheries around the world adopt the new alternative fishing methods so as to reduce the amount of bycatch. People should also be careful while fishing as it is believed that recreational fishing also results in bycatch.